In recent years, high pixel density and size reduction have been progressing in image capturing devices to be mounted on a small-sized electronic device. That is, it is required to obtain a low-height and small-sized image capturing device with excellent resolving power.
An image capturing device with five or six lenses (lens elements) has been attracting attention as an example of the low-height and small-sized image capturing device with excellent resolving power.
In order to obtain the excellent resolving power, it is preferable to satisfactorily correct aberrations by increasing the number of lenses. On the other hand, since an optical total length of an optical system increases, as the number of lenses increases, it leads to increase the height of the image capturing device. In addition, as the number of the lenses increases, factors of manufacturing tolerance generating increase. Since the distance between adjacent lenses is decreased, variations in optical characteristics with respect to a relative positional deviation between the lenses become larger. Therefore, when the number of lenses is too large, it leads to deterioration in productivity of the image capturing device. Accordingly, it is not preferable to increase the number of the lenses. In view of the above, the image capturing device with five or six lenses becomes mainstream, in recent years.
Examples of the image capturing device with five or six lenses include image capturing devices disclosed in PTL 1 and PTL 2.
In the image capturing device, a configuration, in which a plano-concave lens having a surface (object side surface) facing an object side which is a concave surface and a surface (image side surface) facing an image surface side which is a plane is disposed adjacent to an imaging element, is proposed. As the image capturing device, image capturing devices disclosed in PTL 3 and PTL 4 are included. PTL 3 and PTL 4 disclose that aberration is satisfactorily corrected by the configuration.
In addition, in recent years, high pixel density and size reduction have been progressing in image capturing devices to be mounted on a small-sized electronic device. That is, it is required to obtain a low-height and small-sized image capturing device with excellent resolving power.
An image capturing device with five or six lenses (lens elements) has been attracting attention as an example of the low-height and small-sized image capturing device with excellent resolving power.
In order to obtain the excellent resolving power, it is preferable to satisfactorily correct aberrations by increasing the number of lenses. On the other hand, since the optical total length of an optical system increases, as the number of lenses increases, it leads to increase the height of the image capturing device. In addition, as the number of the lenses increases, factors of manufacturing tolerance generating increase. Since the distance between adjacent lenses is decreased, variations in optical characteristics with respect to a relative positional deviation between the lenses become larger. Therefore, when the number of lenses is too large, it leads to deterioration in productivity of the image capturing device. Accordingly, it is not preferable to increase the number of the lenses. In view of the above, the image capturing device with five or six lenses becomes mainstream, in recent years.
Examples of the image capturing device including five or six lenses include image capturing devices disclosed in PTL 1 and PTL 2.
In the image capturing device, a configuration, in which a plano-concave lens having a surface (object side surface) facing an object side is a concave surface and a surface (image side surface) facing an image surface side which is a plane is disposed adjacent to an imaging element, is proposed. As the image capturing device, image capturing devices disclosed in PTL 3 and PTL 4 are included. PTL 3 and PTL 4 disclose that aberration is satisfactorily corrected by the configuration.
Furthermore, in recent years, high pixel density (high resolution) and size reduction (low-height) have been progressing in image capturing devices to be mounted on an electronic device (for example, a mobile device).
As a method for satisfying requirements for high resolution, for example, a method for correcting the aberration by increasing the number of lenses is considered.
However, there are problems in that when the number of lenses increases, (1) a whole length of a lens system becomes increases, and it leads to increase the height of the device, and (2) influence of relative positional deviation between the lenses becomes greater due to an increase of error factors or a close arrangement of the distance between the lenses, and it leads to deteriorate in the productivity.
Accordingly, as a recent image capturing device for an electronic device, an image capturing device with five or six lenses becomes mainstream in consideration of the size and the optical characteristics. The image capturing device with five or six lenses is disclosed in PTL 1 and PTL 2, for example.
In addition, as a technique for obtaining excellent aberration correction effect, for example, in PTL 3 and PTL 4, there are described that a lens of which the object side is the concave surface and the image surface side is a plane is used.